One of the true joys of owning a home is never ceasing to fix or repair something over and over again. haha. That may sound sarcastic but I’m serious! I am able, am willing, and always feels good when done. That especially includes the need to replace rotted window sill twice over.

Lemme show you what I mean.

Here’s two windows at the west end of my home that take on all the weather can throw at them.

While these are not original as the original metal windows we replaced in 2004 – the year I nearly died while in ICU while pregnant with my second child.

Fast-forward over twenty years and my window sills and trim are rotting out.

It doesn’t look too bad if you glance at it, but I know what is brewing there and I want it GONE before winter blows in.

To make this simpler and explain more, I’m sharing this vlog of the process and also writing it out below.

WHERE TO START

First, as with any project like this, I tried to assess what I need before beginning. I bought replacement trim, caulk, and already had screws/nails suited for exterior use as well as tools on hand.

However, you just never know what you’re going to run in to.

Having been apprised of what was done to replace them twenty years ago, I knew that the window had to be built out because of my home and the windows bought at auction (see video for discussion as why). I also thought that pressure-treated wood was used.

So, that meant I could find way more rot than meets the eye.

And… BINGO.

Not only is the first layer of three layers rotted, but ALL THREE. eep!

This is what I find under the first layer of 1″ x 4″ boards – rot in the corners of the 2″ x 4″ boards and also the 1″ x 4″ boards behind them at the butt-joint corners.

No problem. That just meant I had to head back to the store to get a couple more layers of PVC and pressure-treated wood. I make sure to measure before I go and make list of anything else I need to not waste time and trips.

Removing rotting wood is fairly straightforward and can be troublesome in some instances.

Thankfully, once I remove rotted window sill, I have no damage to my exterior wall.

NEXT REPAIR STEPS

At this point, I am hoping I can leave up my shutters and window box but once I get to putting on the new sill and trim, I have to take them off. In that process, doing this by myself, I break one of the corbels from the window box I just rebuilt last fall.

Again, my scrap wood stash comes in handy, and I have one cut, stained and back on in no time.

With that, I’m ready to being cutting the new sill and trim from the PVC and treated wood. Here’s what a “sandwich” of the layers looks like…

The box store inventory doesn’t carry a 1″ x 4″ in treated wood, nor 2″ x 4″ PVC stock either. This will work just fine and last for more than another twenty years or until I replace the windows.

In case you’re wondering, I spent around $200 for the replacement trim whereas a new window that wouldn’t need to be built out was $230 for just the window alone before tax.

This suits my budget better and my windows are still good.

MITERING

Then, I begin making my cuts one window at a time and not assuming both are exactly the same. Additionally, I am using mitered corners instead of the butt-joints to aid in water flow/prevent penetration.

I had to give myself a pat-on-the-back because it’s been a while since making miter cuts and I nailed them! (see my FREE build plans HERE)

Only a couple of times did I need to shorten a piece. If anything, I want to cut a bit long instead of too short.

I use screws to attach this first layer of PVC as well as the next layer of pressure-treated wood. The actual window flange is attached to the 2″x 4″s. Then. the 2″ x 4″ attached to the 1″ x 4″ underneath.

For the final layer, I add the PVC 1″ x 4″s and use galvanized finish nails to attach and use my set tool to punch them just under the surface and cover with caulk.

After that, I also use a ¾” corner round under the window sill as a drip edge.

Last, but not least, I caulk everything and then paint to finish.

Oh, and I did have to trim the one shutter around the meter just a teenie bit to fit perfectly.

COMPLETE

Finally, after two straight days of working, running into a few snags of stripped screws and hopping over bushes every two seconds, the replace rotted window sill project is DONE.

{{applause}}

And my shutters are still holding up well after 20 years and they’re not treated either.

 

With that, I just want to also say that what you speak to others matters.

While I was halfway through putting the new trim on and feeling quite pleased with it going so quickly and I haven’t lost my mojo, a neighbor comes out and says, “You work too hard”.

It stung because the tone wasn’t a compliment and instead of saying, “Hey, great job!”, I felt demeaned.

Use words to lift up and bring smiles, right?

Also, winter is looking to bring us plenty of low temps and possibly snow based on the size and enormous amount of my hickory nuts, the black on woolly bear caterpillars, and even plenty of spiders.

Likewise, the geese have been practicing taking flight, so it’s a’comin!

I’m moving on to my other winterizing projects next. woot!

SHARE

Now you have my how to replace rotted window sill trim and a few tricks to make it a smooth transition. Got questions? Feel free to leave a comment below as well as pin and share to inspire others to give DIY a try. Also, I’d love to hear if you’ve ever tackled something like this.

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While you’re at it, here are other “fun” repairs like how to replace rotted window sill: